"Armed groups are using rape in a brutal, calculated way to punish and terrorise women and girls," said Hillary Margolis, HRW's women's rights researcher, in a statement.

She added: "Every day, survivors live with the devastating aftermath of rape, and the knowledge that their attackers are walking free, perhaps holding positions of power, and to date facing no consequences whatsoever."

According to HRW, most of the abuses not only violate CAR's laws but also constitute war crimes, with some possible crimes against humanity.

The group reported that only 11 of the 296 survivors interviewed had tried to initiate a criminal investigation.

So far, no member of any armed group has been arrested or tried for committing sexual violence.

'Inaccessible justice'

Lewis Mudge, a researcher in the Africa Division at HRW, told Al Jazeera on Thursday that "almost nothing is happening to survivors of these attacks and little is being done to prevent them".

"Survivors of sexual violence need to be given support - medical, psychological and social," he said.

A new government organisation, the Mixed Unit for Rapid Intervention and Suppression of Sexual Violence against Women and Children, is trying to address the plight of survivors.

"If those that we know are responsible for these grave crimes - of rape and violation of human rights - if they are not arrested right now and taken into custody, no victims will have the will to seek justice and that makes justice inaccessible," said Paul Amedee Moye, head of the group.

He added: "You have to talk about zero impunity."

CAR, a former French colony, fell into a protracted political crisis in 2013 after President Francois Bozize was overthrown by the Seleka group, who in turn were driven from power.